As integrated systems reduce in size, low power consumption becomes increasingly important. For example, battery-operated devices such as mobile devices are required to have a long battery life. These devices can include power management systems that take an input voltage, and generate one or more supply voltages for different chips and components on the device. The sensors on the device are usually designed to operate over a wide supply range because the actual supply voltage used to operate the sensor may not be known to the manufacturer of the sensor. Also, different applications, designs or modes of operation may need a same sensor to operate at different voltage levels.
Linear regulator integrated with the sensors can assist with the large supply variation problem. Linear regulators provide a constant output voltage for stable operation of the sensor. Any voltage transients, due to the internal operation of the sensor or due to external disturbances, should be avoided to limit any performance degradation. Linear regulators have a low power efficiency however, particularly when there is a large difference between their input and output voltages. Switching regulators can achieve high power efficiencies while converting voltages, but switching regulators invariably introduce large voltage ripples that can be detrimental to sensor systems that are required to pick up very small signals. These signals can be one or more orders of magnitude smaller than the voltage ripples, thus the switching regulators can introduce noise that can drown out the desired signals.